The lagoon

The Venice lagoon has almost 6000 years. Before its creation, it was a plain composed of sediments transported by rivers such as the Brenta and Piave through the melting ice of the last ice age. During the following centuries, there was, and still is today, phenomena such as the lowering of the ground caused by the gradual compaction and consolidation of alluvial deposits and the rising level of the sea.
The result of all this was the flooding of a large part of the existing plain, except for some areas where the ground was higher areas which became the islands of the Venetian lagoon just born. Then cords dunes of the coast, formed by sand carried by rivers , became the natural border between the lagoon and the Adriatic
Only 5% of the area of the lagoon consists of constantly landmass: the islands, while 20% is represented by the lay, area land awash covered by vegetation particularly resistant to salt. The entire lagoon is crossed by channels of varying depths, marked, at least what are navigable by "tinkering" and "Paline" poles stuck in the ground used to not fail with his boat.
The lagoon is separated from the open sea by lido, these are long strands of sand, sometimes created by man through different methods. Communication with the outside world is through the mouths of ports Lido Malamocco and Chioggia. The water comes from the sea every 6 hours and it is clear from the lagoon after 6am.
Without human intervention, the Venice lagoon could disappear because of the contribution of sediment transported by rivers, indirect rivers responsible for its own creation. The people of Venice had realized this, so that with ingenious hydraulic works, they flicked over the tributary rivers of the lagoon and thus carried the mouths outward.
Currently, as our ancestors did, we dig the channels that are within Venice to remove mud that has accumulated excessively for years.